For intra-BSC handover, the previous encryption is copied from the old lchan,
which of course is not available during inter-BSC handover. Hence the lchan
activation info needs to include an explicit encryption information, and we
must not rely on the presence of the previous lchan to copy encryption
information from.
Add struct lchan_activate_info.encr to allow passing encryption info through
lchan_activate() without requiring a previous struct gsm_lchan to be present.
Instead of copying from the old lchan, always copy encryption info to
lchan_activate_info, and during activation, just before sending the Channel
Activation, copy the lchan_activate_info.encr to the new lchan.
This prepares for upcoming I5b269f50bd2092516bfdf87746196983d3ac49d1 which
obtains the encryption information from an intra-BSC-incoming Handover Request
message.
Related: OS#3842
Related: I5b269f50bd2092516bfdf87746196983d3ac49d1
Change-Id: Ib3d259a5711add65ab7298bfa3977855a17a1642
58cf1b1f66